Preamp with Loudness compensation and Subsonic filter

[quicknick]

I am looking to build a source selector / preamp with tone controls and loudness / subsonic filter (with the ability to bypass the tone control/loudness/subsonic) for my Elliott P101 amplifier. After searching the net I couldn't find a schematic that has all the features I need, so the next approach is trying to combine Rod Elliott's P99 (Subsonic filter) and Dave Erickson "PC-Preamp".

In your opinion, are these two schematics up to the job - I mean offering better performance than a LM1036 for example? Or do you have other circuits that perform better?

And if I go by this path, in what order should they be connected after the source selector? (my guess would be that the subsonic filter goes first)... Also, I will use relays to be able to switch out of the circuit the subsonic filter and I would like to have another switch to take out the tone controls/loudness/balance (something like Source Direct... to have the box behave only as a source selector / volume controller); but as the volume control is part of one stage of the preamp, is this doable? Other than using more relays to disconnect the preamp's volume pot (R10) from the circuit and connect it directly across the signal? Thanks.

Elliott P99: http://sound.westhost.com/project99.htm
PC-Preamp: http://www.djerickson.com/pcpreamp/pdf/Pc_preamp.pdf

 

[quicknick]

Any ideas?

 

[somakmaitra]

Hi ,

I have also searched for the same for a long time but tone control and loudness seems to be a bad word in the diy circles .
There are numerous amps but scant preamps with tone control .
You can use the elektor Single-Chip Tone Control circuit based on 1036.

thats a good option ,or use the P97 and a seperate rumble filter.

somak

 

[wg_ski]

Hi ,
I have also searched for the same for a long time but tone control and loudness seems to be a bad word in the diy circles .
somak

Just buy your 40% tap volume control pot and hang a .033uf cap from the tap - I won't tell anybody.

 

[mlloyd1]

you could also search for the apt holman preamp schematic/manual on this board somewhere. those tone controls had good functionality and (fwiw) were patented.

also, if you can find a schematic for some of the older, high end yamaha "natural sound " series preamps, which had variable loudness controls and (iirc) didn't require the tapped pot.

just keep the lid on the preamp case; i won't tell either ...



mlloyd1

 

[kaos]

I personally have never heard a loudness control that I’ve liked. They all seem off sounding to me, maybe because they don’t follow the Fletcher-Munson curve accurately enough. Maybe because they don’t take into account speaker efficiency or listener position, who knows. Information on tone controls shouldn’t be that hard to find though. Here’s a link to one site, you may already have found it (I won't tell). Figures 2 and 10 look interesting.

http://headwize.com/projects/showfile.php?file=equal_prj.htm

 

[mlloyd1]

i hear you - that is one reason why the yamaha approach was interesting. it was variable from none to full loudness compensation.

mlloyd1

I personally have never heard a loudness control that I’ve liked.

 

[wg_ski]

Blame it on the recording engineers

I personally have never heard a loudness control that I’ve liked. They all seem off sounding to me, maybe because they don’t follow the Fletcher-Munson curve accurately enough.

Maybe because with modern recordings which have the levels ridiculously high your amp is already clipping when the volume pot is set at the 10:00 position.